Fluid operated apparatus

ABSTRACT

An improved fluid motor including a rotationally oscillating piston within a generally sector-shaped chamber, a reciprocating ram element for performing work, linkage means interconnecting the ram element and piston, and means for supplying a fluid under pressure to said chamber, selectively to either one side or the other side of said piston to actuate the latter. The fluid motor of the present invention is disclosed, for exemplary purposes, embodied in an improved punching machine. The motor and machine are so constructed and are of such a configuration that a number of them may be stacked or mounted side by side to provide punching or other operations on very close centers.

Unite States "atet 91 Sawdon [73] Assignee: CkiEiF-a'tionfiffii'rfil'ieh? 22 Filed: 0a. 8, 1971 211 Appl.No.: 187,645

FOREIGN PATENTS OR APPLICATIONS 742,033 12/1955 Great Britain ..83/632 Primary Examiner-J. M. Meister Attorney--Harness, Dickey & Pierce [571 ABSTRACT An improved fluid motor including a rotationally oscillating piston within a generally sector-shaped chamber, a reciprocating ram element for performing work, linkage means interconnecting the ram element and piston, and means for supplying a fluid under pressure to said chamber, selectively to either one side or the other side of said piston to actuate the latter. The fluid motor of the present invention is disclosed, for exemplary purposes, embodied in an improved punching machine. The motor and machine are so constructed and are of such a configuration that a number of them may be stacked or mounted side by side to provide punching or other operations on very close centers.

23 Claims, 5 Drawing Figures FLUID OPERATED APPARATUS BACKGROUND AND SUMMARY OF THE INVENTION The present invention relates generally to fluid motors for use in applications where conventional pneumatic piston and cylinder motors are presently used, for example in the machine tool field. Pneumatic piston and cylinder units are used in a great many different ways for many different functions in connection with the machine tool field, such functions including advancing and retracting tools of various types, advancing and retracting fixtures and the like, advancing and retracting workpieces, ejecting workpieces, workpiece locating, workpiece clamping, etc. Often it is necessary for these pneumatic cylinder units to provide work functions at closely adjacent points on a workpiece or machine. Because of the generally bulky configuration of such units it is often necessary in such cases to provide external linkages or levers extending from the piston rod to the closely adjacent points where the application of a force is desired. The existence of such external levers presents not only a safety hazard, but greatly complicates the apparatus necessary to accomplish a given function. It is also costly. Punching machines are a good example of equipment where it is often necessary to apply a reciprocating force (for punching) on closely spaced centers.

It is therefore a primary object of the present invention to provide a fluid motor which is extremely narrow in one dimension, without a sacrifice in output force capacity, whereby a plurality of such motors may be mounted extremely close to one another, or actually affixed to one another, for performing work at closely adjacent points, without requiring the cumbersome exposed levers commonly used in such applications with pneumatic cylinder units.

Another object of the present invention resides in the provision of an improved punching machine which is extremely narrow in one dimension, without a sacrifice in output force capacity, whereby a plurality of such machines may be mounted extremely close to one another, or actually affixed to one another, for performing work at closely adjacent points, without requiring cumbersome exposed levers.

A further object of the present invention resides in the provision of an improved fluid motor which is relatively simple and inexpensive to manufacture, has relatively few parts, is light in weight, and has great flexibility in being easily adapted to different applications, utilizing standardized components. A related object concerns the provision of an improved punching machine utilizing such fluid motor.

Another object of the present invention resides in the provision of an improved fluid motor having a nonrotating ram.

Other objects, features and advantages of the present invention will become apparent from the following description and the appended claims, taken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a side elevational view, partly in section and with certain parts broken away, of an embodiment of the present invention;

FIG. 2 is a transverse sectional view taken along line 2-2 in FIG. l;

FIG. 3 is an enlarged view of the portion of the structure illustrated within the broken circle in FIG. 1;

FIG. 4 is a front elevational view of a plurality of the mechanisms shown in FIG. 1, stacked or mounted together in such a way that each may operate independently on close centers; and

FIG. 5 is a view similar to FIG. 4 but illustrating a modified manner in which the mechanisms of the present invention may be mounted for operation on minimum centers.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT The present invention is disclosed for exemplary purposes embodied in a simple punching machine, it being appreciated that the fluid motor of the present invention is suited for many different applications where it is desired to obtain work from a source of fluid under pressure. The punch generally comprises a body 10 of the configuration in plan shown in FIG. 1, and having opposite faces 12 and 14 disposed parallel to one another. Secured to faces 12 and 14 by means of threaded fasteners 16 are a pair of flat plates 18 and 20, respectively. Plates 18 and 20 are of the same configuration as the upper portion of body 10, terminating at a lower edge 22. Threaded fasteners 16 are preferably flat head screws threadably engaging suitable tapped holes in body 10, the outer surfaces of plates 18 and 20 being suitably countersunk so that the screw heads are flush with such surfaces.

Body 10 is provided at the lower end thereof with a workpiece receiving throat or recess 24 defining a projection 26 having a vertically extending bore 28 therethrough in which is disposed a conventional punch button 30, held in place and against rotation by a set screw 32. Bore 28 is threaded at the lower end thereof to threadably receive a standard button adjustment screw 34, which is held in place by a lock nut 36. Button 30 and adjustment screw 34 are hollow so that the punched scrap may pass therethrough.

The upper portion of body 10 is provided with a through opening 38 which, in conjunction with plates 18 and 20, defines a chamber. Opening 38 is generally sector-shaped in configuration, comprising a circular cylindrical surface 40 at the apex thereof and disposed opposite thereto an arcuate cylindrical surface 42 having a center of curvature coincident with the centerof curvature of surface 40. The top of opening 38 is defined by a stop surface 44 and a recess 46, the latter communicating with a fluid passageway 48 extending to the outside of the body and provided thereat with a tapped bore 50. The opposite side of opening 38 includes a recess 52, a stop surface 54 and a recess 56. Recess 52 communicated with a fluid passageway 58 which extends through body 10 to the outside thereof where there is provided a tapped bore 60. Recess 56 communicates with a bore 62 extending from opening 38 into recess 24 and being coaxial with bore 28. Tapped bores 50 and 60 are adapted to threadably receive conventional tubing fittings.

Slidably disposed within bore 62 is a ram 64 having disposed within a suitable opening in the lower end thereof a conventional punch 66, which is held in place and against rotation by a set screw 68.v Slidably disposed about the end of punch 66 is a stripper 70 which is spring biased downwardly by a compression spring 72 and held in place by a stripper case 74 threadably secured to the lower end of ram 64, all in the conventional manner. A work piece 66 is shown with a hole being punched therein and with the punch at the bottom of its stroke.

The upper end of ram 64 is provided with oppositely facing flat parallel surfaces 76 and is pivotally secured to a pair oflinks 78 and 80 by means of a pin 82 extending therethrough. The upper ends of links 78 and 80 are pivotally secured by means of a pin 83 to a boss 86 projecting from a piston 86. Pins 82 and 84 are just slightly shorter in length than the thickness of body and are retained in place by plates 18 and 20. Ram 64 is provided with an O-ring or like resilient seal 88 disposed within a suitable annular groove therearound to provide a seal between the ram and bore 62.

Piston 86 is an elongated member generally rectangular in cross section and having in plan at the upper end thereof a cylindrical surface 90 adapted to rotationally fit within surface 40. Piston 86 is just slightly less in thickness than the thickness of body 10 (minimum working clearance) and is adapted to rotate or swing back and forth within opening 38 between a first position in which it engages stop surface 54 (as shown in. FIG. 1) and a second position in which it engages stop surface 44. As can be seen, when piston 86 is in its first position the geometry of the linkage system connecting it with ram 64 is such that the latter is at the bottom of its stroke, and when piston 86 is moved to its second position ram 64 is moved to the top of its stroke, and vice versa. Links 78 and 80 in conjunction with piston 86 define a toggle linkage system so that there is a progressively increasing amplification of the force exerted on ram 64 by piston 86 as the latter moves to its first position, that portion of the stroke of ram 64 being the portion in which it performs work, in this case the punching operation. The linkage system also prevents rotation of ram 64, important when punching non-circular holes.

The free end of piston 86 is disposed closely adjacent surface 42 so that the piston in effect divides the chamber defined by opening 38 and plates 18 and into two chamber portions, one of which communicates with passageway 58 and the other of which communicates with passageway 48. These passageways are connected by means of conventional fittings threadably disposed in tapped bores 60 and 50, respectively, to a conventional fluid supply source for fluid motors (not shown). Recesses 46 and 52 are so located with respect to stop surfaces 38 and 54 that piston 86 cannot move to a position in which both passageways 48 and 58 communicate with the same side thereof. Thus, when fluid is supplied to passageway 48 and passageway 58 placed in communication with the atmosphere or exhaust. piston 86 will be urged in a downward or clockwise direction by the force exerted by the fluid under pressure. until it engages stop surface 54. When fluid under pressure is supplied to passageway 58 and passageway 48 is placed in communication with the atmosphere or exhaust piston 86 is urged upwardly or in a counterclockwise direction by the force of the fluid under pressure, until it engages stop surface 38. The control of the fluid supply in order to so operate the piston back and forth is exactly the same as is conventionally utilized in connection with conventional piston and cylinder fluid motors, in accordance with principals well known in the art.

To effect a reliable and efficient fluid seal between piston 86 and the surfaces defining said chamber, which is important to the efficient utilization of the source fluid, resilient sealing means are provided. This sealing means comprises a pair of generally parallel, annular, continuous grooves 92 and 94 disposed about the entire outer periphery of piston 56, each in a plane perpendicular to the plane of surfaces 12 and 14. Disposed in each groove is a resilient annular sealing element 96, having a generally V-shaped cross section, as best seen in FIG. 3. Elements 96 are arranged so that they face in opposite directions, to thereby maximize the efficiency of the seal in both directions of movement of piston 86.

The pivotal connection between piston 86 and body 10 may be lubricated by means of a lubricating groove 98 communicating with a tapped opening 100 into which may be threadably secured a conventional grease fitting (not shown). Similarly, bore 62 communicates with a tapped opening 102 into which may be provided a conventional grease fitting for lubricating ram 64.

As noted previously, one of the great advantages of the fluid motor of the present invention is the amount of force that can be generated at conventional working pressures in a device which is extremely narrow in width, thereby facilitating the use of a number of such devices extremely close to one another in a machine tool, without requiring external linkages to transmit the working force from a remote point, as with pistion and cylinder units. For example, a pneumatic fluid motor having the general configuration shown in the drawing and a 1 /2 inch overal thickness or width (a 1 inch body and two A inch plates) has been found to be capable of exerting a 2,000-pound force with an psi air supply. This is a substantially greater force than is exerted by a conventional pistion and cylinder unit 1% inches wide operating at the same pressure, even one having a similar toggle linkage (necessarily external). Greater forces may be achieved by designing the device with a longer and/or wider piston, and/or by moving the pivotal connection at pin 84 closer to the center of rotation of piston 86.

Because of this narrow width and flat side configuration the present mechanisms may be stacked or mounted side by side in a row, utilizing as many as is desired, such as shown in FIG. 4. Using the above example this assembly would be capable of punching holes on 1 /2 inch centers, with each punch being operable independently. In addition, using standardized parts of a given dimension it is possible to fabricate fluid motors having greater force capabilities and/or minimum punching centers by merely affixing two or more pistons together side by side within two or more bodies affixed together side by side, eliminating the inside plates and utilizing only two plates on the outside of the assembly. Such an assembly is shown in FIG. 5. For this purpose, a pair of holes 104 may be provided through each body 10 to receive dowel pins for aligning and mounting two or more bodies together. Similarly, each piston 86 may be provided with a pair of holes 106 to facilitate a similar joining of two or more pistons 86. Single or multiple rams may be utilized, depending on the application. Using the above example in this manner would result in an assembly capable of punching on 1 inch centers, although all of the punches would have to operate in unison. The design flexibility of the present invention in different applications, with a minimum number of standardized parts, is thus substantial.

Thus, there is disclosed in the above description and in the drawing exemplary embodiments of the invention which fully and effectively accomplish the objects thereof. However, it will be apparent that variations in the details of construction and application may be indulged in without departing from the sphere of the invention herein described, or the scope of the appended claims.

I claim:

1. A fluid device comprising: a body member having a chamber therein; piston means disposed in said chamber for rotational oscillation therein; sealing means for sealing said piston means with respect to the walls of said chamber in all operating positions of said piston means; reciprocating ram means disposed in said body member; and linkage means pivotally interconnecting said piston means and said ram means.

2. A fluid device as claimed in claim 1, wherein there is a pivotal connection between said piston means and said body member comprising a convex cylindrical surface on said piston means and a complementary concave cylindrical surface in said chamber, both of said cylindrical surfaces having an arcuate length greater than 180, said concave surface rotationally supporting said convex surface.

3. A fluid device as claimed in claim 1, further comprising support means formed integrally with said body member adjacent said free end of said ram means, said support means lying on the axis of reciprocation of said ram means, punch means mounted on said free end of said ram means, and button means mounted on said support means in alignment with said punch means.

4. A fluid device comprising: housing means having a chamber therein, said chamber having substantially parallel side walls opposing one another; piston means mounted in said chamber for rotational movement about an axis of rotation disposed adjacent one end of said piston and extending perpendicular to said chamber side walls; means defining a first cylindrical surface in said chamber between said chamber walls, said first cylindrical surface having a center of curvature coincident with said rotational axis and being disposed adjacent said one end of said piston means; means defining a second cylindrical surface in said chamber between said chamber walls, said second cylindrical surface having a center of curvature coincident with said rotational axis and being disposed immediately adjacent the opposite end of said piston means; means sealing said piston means with respect to said first and second cylindrical surfaces and said side walls. whereby said piston means divides said chamber into first and second separate chamber portions; first passage means in said housing means for communicating fluid into and out of said first chamber portion; second passage means in said housing means for communicating fluid into and out of said second chamber portion; ram means extending through said housing means; and linkage means pivotally connecting said piston means to said ram means, whereby back and forth rotation of said piston means will cause said ram means to reciprocate.

5. A fluid device as claimed in claim 4, wherein said ram means reciprocates along a longitudinal axis which approximately intersects said rotational axis.

6. A fluid device as claimed in claim 5, wherein said linkage means is pivotally connected to said piston means at a point thereon disposed between said axis of rotation and said second cylindrical surface.

7. A fluid device as claimed in claim 4, wherein said linkage means includes a link pivotally connected at one end to said ram means and at the other end to said piston means, said piston means being mounted so that it can rotate to a position where the axis of rotation of its pivotal connection with said other end of said link approximately intersects said longitudinal axis.

8. A fluid device as claimed in claim 7, wherein stop means is provided in said chamber for stopping the rotational movement of said piston means in one direction at a point where the axis of rotation of its pivotal connection with said other end of said link approximately intersects said longitudinal axis.

9. A fluid device as claimed in claim 4, wherein said linkage means is a toggle linkage, whereby said ram means is capable of exerting a working force greater than the force exerted on it by said piston means.

10. A fluid device as claimed in claim 4, wherein said sealing means comprises a continuous groove disposed about the entire outer periphery of said piston means in a plane perpendicular to the plane of said side walls,

and a continuous annular resilient sealing element disposed in said groove.

11. A fluid device as claimed in claim 10, wherein said resilient element has a resilient flange thereon adapted to wipe the adjacent surfaces of said housing means as said piston rotates.

12. A fluid device as claimed in claim 11, wherein said sealing means comprises a second continuous groove and resilient element of identical configuration and disposed parallel to said first groove and sealing element. Y

13. A fluid device as claimed in claim 12, wherein the resilient flange on said second resilient element extends in a direction opposite to that of the resilient flange on said first resilient element.

14. A fluid device as claimed in claim 4, wherein stop means are provided in said chamber for limiting pivotal movement of said piston means in both directions.

15. A punching machine comprising: housing means having a chamber therein, said chamber having substantially parallel side walls opposing one another; piston means mounted in said chamber for rotational movement about an axis of rotation disposed adjacent one end of said piston and extending perpendicular to said chamber side walls; means defining a first cylindrical surface in said chamber between said chamber walls, said first cylindrical surface having a center of curvature coincident with said rotational axis and being disposed adjacent said one end of said piston means; means defining a second cylindrical surface in said chamber between said chamber walls, said second cylindrical surface having a center of curvature coincident with said rotational axis and being disposed immediately adjacent the opposite end of said piston means; means sealing said piston means with respect to said first and second cylindrical surfaces and said side walls, whereby said piston means divides said chamber into first and second separate chamber portions; first passage means in said housing means for communicat-- ing fluid into and out of said first chamber portion; second passage means in .said housing means for communicating fluid into and out of said second chamber portion; ram means having a free end extending through said housing means to a point outside thereof; linkage means pivotally connecting said piston means to said ram means, whereby back and forth rotation of said piston means will cause said ram means to reciprocate; punch means mounted to said free end of said ram means; and button means connected to said housing means in alignment with said punch means.

16. A fluid device comprising: a body having oppositely disposed flat parallel faces having an opening therethrough; a flat plate mounted on each of said faces whereby the inside faces of said plates and said opening define a chamber; piston means mounted in said chamber for rotational movement about an axis of rotation disposed adjacent one end of said piston and extending perpendicular to said faces; means defining a first cylindrical surface in said chamber between said faces, said first cylindrical surface having a center of curvature coincident with said rotational axis and being disposed adjacent said one end of said piston means; means defining a second cylindrical surface in said chamber between said faces, said second cylindrical surface having a center of curvature coincident with said rotational axis and being disposed immediately adjacent the opposite end of said piston means; means sealing said piston means with respect to said first and second cylindrical surfaces and said inside faces of said plates, whereby said piston means divides said chamber into first and second separate chamber portions; first passage means in said body for communicating fluid into and out of said first chamber portion; second passage means in said body for communicating fluid into and out of said second chamber portion; ram means having a free end extending through said body; and linkage means pivotally connecting said piston means to said ram means, whereby back and forth rotation of said piston means will cause said ram means to reciprocate.

17. A fluid device as claimed in claim 16, wherein said body is provided with accurately located through holes adapted to receive dowel pins for locating and joining a plurality of said bodies together.

18. A fluid device as claimed in claim 16, wherein said piston means is provided with accurately located through holes adapted to receive dowel pins for locating and joining a plurality of said piston means together.

19. A fluid device as claimed in claim 16, further comprising support means formed integrally with said body adjacent said free end of said ram means, said support means lying on the axis of reciprocation of said ram means, punch means mounted on said free end of said ram means, and button means mounted on said support means in alignment with said punch means.

'20. A fluid device as claimed in claim 19, further comprising means defining a workpiece receiving throat in said body in transverse alignment with said button means. I H

21. A punching machine comprising: a first body member having oppositely disposed substantially parallel outside faces and having an opening therethrough; a second body member of substantially identical construction affixed to said first body member in face to face relationship with the respective openings in each alignment; first piston means disposed in said opening in said first body member for rotational reciprocation therein, said piston means having a width just slightly less than the thickness of said first body means; second piston means disposed in the opening in said second body member for rotational reciprocation therein, said second piston means having a width just slightly less than the thickness of said second body means, said first and second piston means being affixed to one another in side by side relationship; plate means sealingly disposed on the exposed outside faces of said body members to fully cover the combined openings; sealing means for sealing both of said piston means with respect to each other, said body members and said plate means, in all operating positions of said piston means; reciprocating ram means disposed in said body member; and linkage means pivotally interconnecting one of said piston means and said ram means.

22. A fluid device as claimed in claim 21, wherein both said piston means are provided with accurately located through holes adapted to receive dowel pins for locating and joining them together.

23. A fluid device as claimed in claim 21, wherein both said body members are provided with accurately located through holes adapted to receive dowel pins for locating and joining them together. 

1. A fluid device comprising: a body member having a chamber therein; piston means disposed in said chamber for rotational oscillation therein; sealing means for sealing said piston means with respect to the walls of said chamber in all operating positions of said piston means; reciprocating ram means disposed in said body member; and linkage means pivotally interconnecting said piston means and said ram means.
 2. A fluid device as claimed in claim 1, wherein there is a pivotal connection between said piston means and said body member comprising a convex cylindrical surface on said piston means and a complementary concave cylindrical surface in said chamber, both of said cylindrical surfaces having an arcuate length greater than 180*, said concave surface rotationally supporting said convex surFace.
 3. A fluid device as claimed in claim 1, further comprising support means formed integrally with said body member adjacent said free end of said ram means, said support means lying on the axis of reciprocation of said ram means, punch means mounted on said free end of said ram means, and button means mounted on said support means in alignment with said punch means.
 4. A fluid device comprising: housing means having a chamber therein, said chamber having substantially parallel side walls opposing one another; piston means mounted in said chamber for rotational movement about an axis of rotation disposed adjacent one end of said piston and extending perpendicular to said chamber side walls; means defining a first cylindrical surface in said chamber between said chamber walls, said first cylindrical surface having a center of curvature coincident with said rotational axis and being disposed adjacent said one end of said piston means; means defining a second cylindrical surface in said chamber between said chamber walls, said second cylindrical surface having a center of curvature coincident with said rotational axis and being disposed immediately adjacent the opposite end of said piston means; means sealing said piston means with respect to said first and second cylindrical surfaces and said side walls, whereby said piston means divides said chamber into first and second separate chamber portions; first passage means in said housing means for communicating fluid into and out of said first chamber portion; second passage means in said housing means for communicating fluid into and out of said second chamber portion; ram means extending through said housing means; and linkage means pivotally connecting said piston means to said ram means, whereby back and forth rotation of said piston means will cause said ram means to reciprocate.
 5. A fluid device as claimed in claim 4, wherein said ram means reciprocates along a longitudinal axis which approximately intersects said rotational axis.
 6. A fluid device as claimed in claim 5, wherein said linkage means is pivotally connected to said piston means at a point thereon disposed between said axis of rotation and said second cylindrical surface.
 7. A fluid device as claimed in claim 4, wherein said linkage means includes a link pivotally connected at one end to said ram means and at the other end to said piston means, said piston means being mounted so that it can rotate to a position where the axis of rotation of its pivotal connection with said other end of said link approximately intersects said longitudinal axis.
 8. A fluid device as claimed in claim 7, wherein stop means is provided in said chamber for stopping the rotational movement of said piston means in one direction at a point where the axis of rotation of its pivotal connection with said other end of said link approximately intersects said longitudinal axis.
 9. A fluid device as claimed in claim 4, wherein said linkage means is a toggle linkage, whereby said ram means is capable of exerting a working force greater than the force exerted on it by said piston means.
 10. A fluid device as claimed in claim 4, wherein said sealing means comprises a continuous groove disposed about the entire outer periphery of said piston means in a plane perpendicular to the plane of said side walls, and a continuous annular resilient sealing element disposed in said groove.
 11. A fluid device as claimed in claim 10, wherein said resilient element has a resilient flange thereon adapted to wipe the adjacent surfaces of said housing means as said piston rotates.
 12. A fluid device as claimed in claim 11, wherein said sealing means comprises a second continuous groove and resilient element of identical configuration and disposed parallel to said first groove and sealing element.
 13. A fluid device as claimed in claim 12, wherein the resilient flange on said second resilient element extends in a direction opposite to that of the resilient flange on said first reSilient element.
 14. A fluid device as claimed in claim 4, wherein stop means are provided in said chamber for limiting pivotal movement of said piston means in both directions.
 15. A punching machine comprising: housing means having a chamber therein, said chamber having substantially parallel side walls opposing one another; piston means mounted in said chamber for rotational movement about an axis of rotation disposed adjacent one end of said piston and extending perpendicular to said chamber side walls; means defining a first cylindrical surface in said chamber between said chamber walls, said first cylindrical surface having a center of curvature coincident with said rotational axis and being disposed adjacent said one end of said piston means; means defining a second cylindrical surface in said chamber between said chamber walls, said second cylindrical surface having a center of curvature coincident with said rotational axis and being disposed immediately adjacent the opposite end of said piston means; means sealing said piston means with respect to said first and second cylindrical surfaces and said side walls, whereby said piston means divides said chamber into first and second separate chamber portions; first passage means in said housing means for communicating fluid into and out of said first chamber portion; second passage means in said housing means for communicating fluid into and out of said second chamber portion; ram means having a free end extending through said housing means to a point outside thereof; linkage means pivotally connecting said piston means to said ram means, whereby back and forth rotation of said piston means will cause said ram means to reciprocate; punch means mounted to said free end of said ram means; and button means connected to said housing means in alignment with said punch means.
 16. A fluid device comprising: a body having oppositely disposed flat parallel faces having an opening therethrough; a flat plate mounted on each of said faces whereby the inside faces of said plates and said opening define a chamber; piston means mounted in said chamber for rotational movement about an axis of rotation disposed adjacent one end of said piston and extending perpendicular to said faces; means defining a first cylindrical surface in said chamber between said faces, said first cylindrical surface having a center of curvature coincident with said rotational axis and being disposed adjacent said one end of said piston means; means defining a second cylindrical surface in said chamber between said faces, said second cylindrical surface having a center of curvature coincident with said rotational axis and being disposed immediately adjacent the opposite end of said piston means; means sealing said piston means with respect to said first and second cylindrical surfaces and said inside faces of said plates, whereby said piston means divides said chamber into first and second separate chamber portions; first passage means in said body for communicating fluid into and out of said first chamber portion; second passage means in said body for communicating fluid into and out of said second chamber portion; ram means having a free end extending through said body; and linkage means pivotally connecting said piston means to said ram means, whereby back and forth rotation of said piston means will cause said ram means to reciprocate.
 17. A fluid device as claimed in claim 16, wherein said body is provided with accurately located through holes adapted to receive dowel pins for locating and joining a plurality of said bodies together.
 18. A fluid device as claimed in claim 16, wherein said piston means is provided with accurately located through holes adapted to receive dowel pins for locating and joining a plurality of said piston means together.
 19. A fluid device as claimed in claim 16, further comprising support means formed integrally with said body adjacent said free end of said ram means, said support means lying on the axis of recipRocation of said ram means, punch means mounted on said free end of said ram means, and button means mounted on said support means in alignment with said punch means.
 20. A fluid device as claimed in claim 19, further comprising means defining a workpiece receiving throat in said body in transverse alignment with said button means.
 21. A punching machine comprising: a first body member having oppositely disposed substantially parallel outside faces and having an opening therethrough; a second body member of substantially identical construction affixed to said first body member in face to face relationship with the respective openings in each alignment; first piston means disposed in said opening in said first body member for rotational reciprocation therein, said piston means having a width just slightly less than the thickness of said first body means; second piston means disposed in the opening in said second body member for rotational reciprocation therein, said second piston means having a width just slightly less than the thickness of said second body means, said first and second piston means being affixed to one another in side by side relationship; plate means sealingly disposed on the exposed outside faces of said body members to fully cover the combined openings; sealing means for sealing both of said piston means with respect to each other, said body members and said plate means, in all operating positions of said piston means; reciprocating ram means disposed in said body member; and linkage means pivotally interconnecting one of said piston means and said ram means.
 22. A fluid device as claimed in claim 21, wherein both said piston means are provided with accurately located through holes adapted to receive dowel pins for locating and joining them together.
 23. A fluid device as claimed in claim 21, wherein both said body members are provided with accurately located through holes adapted to receive dowel pins for locating and joining them together. 